TUBERCULOSIS. 313 



and remote from the primary lesion (due to the presence 

 of tubercles), and a widespread invasion of the lungs, 

 liver, kidneys, peritoneum, and other organs and tissues, 

 with tuberculous tissue in a more or less advanced con- 

 dition of necrosis. Sometimes there are no tubercles 

 discoverable at the point of inoculation. There is no 

 regularity in the distribution of the disease. Tubercle 

 bacilli are demonstrable in immense numbers in all the 

 diseased tissues. The disease as seen in the guinea-pig is 

 more extended than in other animals because of its greater 

 susceptibility, and the death of the animal is more rapid 

 than in other species for the same reason. Intraperi- 

 toneal injection of tubercle bacilli in guinea-pigs causes 

 a much more rapid disease than that following sub- 

 cutaneous inoculation, and is accompanied with wide- 

 spread lesions of the abdominal organs. The animals 

 die in from three to six weeks. In rabbits the lesion 

 runs a longer course with similar lesions. In bovine 

 animals and sheep the infection is usually first seen in 

 the alimentary apparatus and associated organs, and may 

 be limited to them. Pulmonary disease sometimes oc- 

 curs. In man the disease is chiefly pulmonary, though 

 gastro-intestinal and general miliary forms are common. 

 The development of the lesions in whatever tissue or 

 animal always depends upon the distribution of the 

 bacilli by the lymph or the blood. 



The experiments of Koch, Prudden and Hodenphyl, 

 and others have shown that when dead tubercle bacilli 

 are injected into the subcutaneous tissues of rabbits 

 small local abscesses develop in the course of a couple 

 of weeks, showing that the tubercle bacilli are chemotac- 

 tically potent. 



While it is extremely interesting to observe that this 

 chemotactic property exists, it seems to be by some other 

 irritant that most of the lesions of tuberculosis are caused. 

 When the dead tubercle bacilli, instead of being injected 

 en masse into the areolar tissue, are so introduced into 

 the body — as by intravenous injection — as to disseminate 



